Asphalt-based roofing materials, such as roofing shingles, roll roofing and commercial roofing, are installed on the roofs of buildings to provide protection from the elements, and to give the roof an aesthetically pleasing look. Typically, the roofing material is constructed of a substrate such as a glass fiber mat or an organic felt, an asphalt coating on the substrate, and a surface layer of granules embedded in the asphalt coating. A common method for the manufacture of asphalt shingles is the production of a continuous sheet of granule covered, asphalt coated material followed by a shingle cutting operation which cuts the material into individual shingles having normally covered (i.e., by a subsequently laid course of shingles) headlap portions and normally exposed tab portions.
A conventional single layer tabbed shingle 10, as shown in FIGS. 1 and 1A, includes a single asphalt coated shingle sheet 11 defining a continuous headlap portion 17 and a slotted or discontinuous tab portion 18. As shown in FIG. 1A, the shingle sheet 11 includes a substrate layer 12 (e.g., fiberglass mat), upper and lower asphalt coating layers 13, 14 (generally formed from layers of hot, melted asphalt) adhered to the substrate layer 12, a layer of granules 15 (e.g., ceramic roofing grade granules of a variety of different particle sizes and colors) adhered to the upper asphalt coating 13 to define an upper surface 10a of the shingle, and a layer of backdust 16 (e.g., pulverized sand, talc, mica, calcium carbonate, or ground recycled glass) adhered to the lower asphalt coating 14 to define a lower surface 10b of the shingle 10.
A conventional two-layer or laminated shingle 20, as shown in FIGS. 2 and 2A, includes an asphalt coated overlay sheet 21 having a continuous headlap portion 27 and a tabbed or slotted tab portion 28 adhered to an upper surface of an asphalt coated underlay sheet 31 to define a tab portion 38 of the shingle 20. The overlay and underlay sheets 21, 31 each include a substrate layer 22, 32, upper and lower asphalt coating layers 23, 33, 24, 34 adhered to the substrate layer, a layer of granules 25, 35 adhered to at least the exposed portions of the upper asphalt coating 23, 33 to define an upper surface 20a of the shingle, and a layer of backdust 26, 36 adhered to at least the exposed portions of the lower asphalt coating 24, 34 to define a lower surface 20b of the shingle 20. The overlay and underlay sheets 21, 31 may be adhered to each other by the abutting portions of the hot melt asphalt coating layers 24, 33 (with these portions free of granules to allow for adhesion), or by a post-applied pattern of adhesive 29a (e.g., asphalt adhesive).
During a typical shingle manufacturing process, a pattern of adhesive is applied to the shingle, either on the upper surface of the headlap portion (as shown at 19a in FIG. 1 and at 29 in FIGS. 2 and 2A) or on the lower surface of the tab portion (as shown at 19b in FIGS. 1 and 1A and at 39 in FIGS. 2 and 2A), so that the headlap portions of a lower course of shingles on a roof will adhere to the tab portions of a subsequently laid course of shingles on the roof. The resulting adhesive bond helps to prevent wind uplift of the shingles on the roof.
Self-sealing asphalt shingles are typically packaged, shipped, and stored in a bundle of stacked shingles. To prevent adhesion of a shingle's adhesive pattern to an adjacent shingle, a removable release tape or strip may be applied to the line of adhesive, or alternatively, the portion of the adjacent shingle in facing alignment with the adhesive pattern may be provided with a non-stick surface to allow for easy separation of the shingles.